In the Torah portion of Bamidbar the verse states:1 “These are the children of Aharon and Moshe on the day that G‑d spoke to Moshe on Mount Sinai. These are the names of Aharon’s sons — Nadav, the firstborn, Avihu, Elazar and Isamar.”

In commenting on the words “These are the children of Aharon and Moshe,” Rashi notes: “He only mentions Aharon’s children.”

So why is Moshe included here?2

Rashi goes on to explain that Aharon’s children are also called Moshe’s children, inasmuch as “Whoever teaches his friend’s son Torah is considered as if he bore him.”3 Since Moshe singled out Aharon’s children for instruction before he taught the rest of the populace,4 Aharon’s children are considered as if they were Moshe’s.

Rashi goes on to comment on the words “on the day that G‑d spoke to Moshe”: “They [then] became his children, for he taught them that which he learned from the A-lmighty.”

What is Rashi adding to his previous explanation that by Moshe teaching Aharon’s sons Torah they are considered his?

Rashi is addressing the following difficulty: The verse explicitly states “These are the children of Aharon and Moshe,” i.e., they are Moshe’s children to the same degree that they are Aharon’s. However, these were Aharon’s children in the literal sense and Moshe’s only in the figurative sense — “Whoever teaches his friend’s son Torah is considered as if he bore him.” How, then, are they considered Moshe’s children to the same extent as they are Aharon’s?

This, Rashi says, is addressed when the verse goes on to state “on the day that G‑d spoke to Moshe”: It stresses, Rashi explains, that the Torah Moshe taught Aharon’s children was identical to that which he learned from the A-mighty. This Torah study therefore caused such a mighty impact that “they became his children, i.e., Moshe’s teaching transformed their spiritual being, and they literally became his.

The explanation is as follows. In preparation for Mattan Torah, G‑d instructed Moshe to tell the Jewish people: “Now if you obey Me and keep My covenant, you shall be My special treasure among all nations … You will be a kingdom of priests and a holy nation to Me.”5

Mattan Torah thus brought about a radical change within the Jewish people, to the extent that our very being underwent a fundamental transformation. Prior to this, we were a nation “among all nations,” but through Mattan Torah we became exceptional and distinct — a “special treasure among all nations,” “a kingdom of priests and a holy nation.”

This is why Mattan Torah involved G‑d revealing Himself to us with might , “mighty sounds … flames … and the blast of the shofar.”6 The Ten Commandments as well were heard by the Jews from “the mouth of the A-mighty.”7 This brought about a change in our very being.

Since our becoming a “special treasure” is connected with Mattan Torah and depends on “keeping My covenant,” i.e., “observing the Torah,”8 it is to be understood that the power that Mattan Torah has to change the being of the Jew was placed within Torah.

Rashi therefore emphasizes “for he taught them that which he learned from the A-mighty:” Since the Torah that Moshe taught Aharon’s children was the Torah that he himself had learned from the A-mighty, it had within it the power of Mattan Torah , the power that can change the very being of a Jew. Aharon’s children were therefore considered Moshe’s own, for he truly bore them in a spiritual manner.

But wasn’t this aspect of Torah already accomplished within all Jews at the time of Mattan Torah ? What special dimension was added when Moshe later singled out Aharon’s children for instruction?

Rashi provides the answer by stating, “for he taught them that which he learned from the A-mighty.” In order to bring about a spiritual rebirth through Torah, it is not enough to merely hear the words, even as the Jewish people heard the first two of the Ten Commandments directly from G‑d. Rather the Torah must be learned and absorbed.

This was accomplished when Moshe “taught them that which he learned from the A-mighty.” Moshe not only related the other eight commandments to the Jewish people, he taught it to them in a thorough manner.9 Since he learned with Aharon’s children in particular, they in particular are considered his children.

Based on Likkutei Sichos , Vol. XXIII, pp. 8-13.